The present invention relates generally to a rotary finishing device, and more particularly to a flap-type rotary finishing device having an epoxy attachment of the finishing media to a hub of the flap wheel.
Rotary finishing tools are well known and typically include pieces or strips of a finishing medium. Such tools have proven to be very effective in the finishing of a wide variety of components such as those made from metal or the like. An exemplary rotary finishing tool utilizes generally rectangular pieces of abrasive paper, such as sandpaper, to provide a rotary abrasive device.
One of the more common rotary finishing tools or devices is known in the art as a flap wheel. These flap wheels typically have annular arrays of flexible finishing strips and are commonly used in the finishing art. Most conventional rotary finishing devices consist of flexible strips each comprising sheets of material for finishing a surface of a piece. Many of these rotary finishing devices have abrasive particles bonded on one face thereof. Such rotary abrasive devices are useful for contoured polishing, cutting, or surface abrading of a variety of metal surfaces.
Various fabrication methods for such a rotary device are known. One such conventional method requires that the finishing sheets have two notches in their opposite side edges near the base end of each strip. As the strips are arranged in an annular array, the notches form concentric circular depressions on opposite sides of the annular array. Suitable circular reinforcement mechanisms, such as two metallic end caps are mounted on opposite sides of the array. Each end cap has an inwardly extending lip, which engages the circular depressions to mechanically grip the inner ends of the finishing strips. This method thus relies on friction created between the two metallic end caps to maintain the base ends of the strips in contact with a hub of the rotary device. Although a rotary finishing device of this configuration performs suitably, its manufacture is rather expensive and requires two notches to be formed in each strip prior to assembly. The forming of these notches is both time consuming and costly. Further, the notches must be aligned properly with respect to each other to receive accurate placement of the metal end caps.
Another known fabrication method for a rotary finishing device involves attaching the strips to an aluminum clip, such as by stapling. The metal clip with the attached strips is then loaded into a metal hub. A plurality of pins are then used to secure the hub to an end cap. These pins maintain the strips in communication with the metal hub, such that it is relatively difficult for the strips to become disengaged from the hub during polishing. However, these rotary devices are also relatively expensive and also require a relatively cumbersome assembly process.
Yet another known fabrication process involves attaching the finishing media through the use of a suitable adhesive. This adhesive, such as an epoxy, is applied to the strips at their base ends to bond them to one another to form a unitary structure. The adhesive itself thus becomes the hub. Alternatively, a cardboard center is utilized to control the flow of adhesive. While these rotary devices are relatively inexpensive to produce, they are prone to breakage issues after high use. This breakage typically occurs due to failure of the epoxy, which is the weakest part of the device, as a result of the application of significant force during usage. When this breakage or failure of the rotary device occurs, a portion of the epoxy, together with the adhered strips, typically separates from the device. This results in an imbalanced rotary device, which requires replacement. Additionally, when the breakage occurs, because of the relatively high operating speeds of these devices, the separated portion can become a projectile, which can raise safety concerns or cause damage to the finishing device or surrounding apparatus.
Therefore, a need exists for a rotary finishing device that is relatively inexpensive to manufacture, but has sufficient strength to withstand the high operating speeds to which these devices are subjected.